Several prior art devices are known which include a variable speed air motor for driving different rotatable shaft driven tools used in orthopedic surgery such as saws, pin or wire drivers, universal chucks and reamer drivers. While at least one of the prior art devices is able to adequately drive each such known tool, all such known prior art devices have lacked the degree of versatility that might be desired to properly drive all of the different tools that are used during various orthopedic procedures.
For example, heretofore, many such devices have provided only one output shaft driven at a single speed ratio with respect to the speed of the air motor which limits the range of speeds available at that output shaft to drive different tools. While one such known device available from Howmedica, Rutherford, N.J., and known as the "Chirodrill".TM. provides two concentric output shafts driven at different speed ratios with respect to the speed of its air motor and thus provides two substantially different ranges of output speeds by which tools can be driven (e.g., a high output speed range at one shaft and a substantially lower output speed drive range at the other shaft), that device does not provide a cannulated or hollow drive shaft so that procedures such as pin or wire driving or following a guide wire that require such a hollow drive shaft are prevented and the versatility of the device is restricted.